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by j_shreyans » Wed Oct 29, 2014 9:08 am
A driver paid n dollars for auto insurance for the year 1997. This annual premium was raised by p percent for the year 1998; for each of the years 1999 and 2000, the premium was decreased by 1/6 from the previous year's figure. If the driver's insurance premium for the year 2000 was again n dollars, what is the value of p?

A)12
B)100/3
C)36
D)44
E)50

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by GMATGuruNY » Wed Oct 29, 2014 9:25 am
j_shreyans wrote:A driver paid n dollars for auto insurance for the year 1997. This annual premium was raised by p percent for the year 1998; for each of the years 1999 and 2000, the premium was decreased by 1/6 from the previous year's figure. If the driver's insurance premium for the year 2000 was again n dollars, what is the value of p?

A)12
B)100/3
C)36
D)44
E)50
Let n = 100.
We can PLUG IN THE THE ANSWERS, which represent the value of p.
When the correct answer choice is plugged in, the premium in 2000 = n = 100.

Answer choice D: 44
Since the premium increases by p% in 1998, the premium in 1998 = 100 + 44% of 100 = 144.
Since the premium decreases by 1/6 in 1999, the premium in 1999 = 144 - (1/6)(144) = 144 - 24 = 120.
Since the premium deceases by another 1/6 in 2000, the premium in 2000 = 120 - (1/6)(120) = 120 - 20 = 100.
Success!

The correct answer is D.
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by Brent@GMATPrepNow » Wed Oct 29, 2014 9:57 am
j_shreyans wrote:A driver paid n dollars for auto insurance for the year 1997. This annual premium was raised by p percent for the year 1998; for each of the years 1999 and 2000, the premium was decreased by 1/6 from the previous year's figure. If the driver's insurance premium for the year 2000 was again n dollars, what is the value of p?

A)12
B)100/3
C)36
D)44
E)50
Here's an algebraic solution.

First recognize that increasing a value by p percent is the same as multiplying by (100 + p)/100
For example, increasing a value by 7% is the same as multiplying by (100 + 7)/100 [i.e. 1.07]
Likewise, increasing a value by 25% is the same as multiplying by (100 + 25)/100 [i.e. 1.25]

Also, recognize that decreasing a value by 1/6 is the same as multiplying by 5/6


Okay, let's begin.

Premium for 1997: n
Premium for 1998: [(100 + p)/100]n
Premium for 1999: (5/6)[(100 + p)/100]n
Premium for 2000: (5/6)(5/6)[(100 + p)/100]n

We're told that the premium for 2000 is n.
So, we can write: (5/6)(5/6)[(100 + p)/100]n = n
Divide both sides by n to get: (5/6)(5/6)[(100 + p)/100] = 1
Simplify: (25/36)[(100 + p)/100] = 1
Simplify: (25)(100 + p)/(36)(100) = 1
Simplify: (100 + p)/(36)(4) = 1
So we know that 100 + p = (36)(4)
Simplify: 100 + p = 144
So, p = 44

Answer: D

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by Johnniewales » Tue Dec 08, 2015 6:50 am
Please what determines when we plug in? In some cases, we plug in
And the equation becomes messy. Then sometimes we don't plug in
Then realized we should have. Please help
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by [email protected] » Tue Dec 08, 2015 9:39 am
Hi Johnniewales,

You ask a good question - much of the information that you're seeking will come from experience/practice though. Many of the Quant questions that you'll face on Test Day can be solved by TESTing VALUES or TESTing THE ANSWERS, while others are essentially just 'math questions' that require a few calculations to get to the solution. The good news is that GMAT is a predictable, standardized Test, so once you learn to spot the patterns in the questions, then you'll be able to select the most efficient way to go about solving the question.

You should post any GMAT questions that you have in these Forums, so that you can see how Experts and other Users solve them.

1) How long have you been studying?
2) What resources have you been using?

GMAT assassins aren't born, they're made,
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by Johnniewales » Tue Dec 08, 2015 2:13 pm
Thanks Rich,

I have been studying since July but just started using MGMAT series text books and the 60day guide in November,
I will be taking the exams in January 2016

Regards

Johnniewales
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by [email protected] » Tue Dec 08, 2015 10:38 pm
Hi Johnniewales,

Since you've been studying for some time, how have you been scoring on your practice CATs (including the Quant and Verbal Scaled Scores)? And what is your goal score?

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by Johnniewales » Wed Dec 09, 2015 9:19 am
Hi Rich,

I haven't been doing well, my score has just been between 420-480
Break down

Quant- 27
Verbal -22

My target score is between 700-750

I really need to improve my scores

Thanks
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by [email protected] » Wed Dec 09, 2015 10:10 am
Hi Johnniewales,

I've sent you a PM with some suggestions.

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by prada » Tue Feb 02, 2016 5:49 pm
[email protected] wrote:Hi Johnniewales,

You ask a good question - much of the information that you're seeking will come from experience/practice though. Many of the Quant questions that you'll face on Test Day can be solved by TESTing VALUES or TESTing THE ANSWERS, while others are essentially just 'math questions' that require a few calculations to get to the solution. The good news is that GMAT is a predictable, standardized Test, so once you learn to spot the patterns in the questions, then you'll be able to select the most efficient way to go about solving the question.

You should post any GMAT questions that you have in these Forums, so that you can see how Experts and other Users solve them.

1) How long have you been studying?
2) What resources have you been using?

GMAT assassins aren't born, they're made,
Rich
Hey Rich, when you say
The good news is that GMAT is a predictable, standardized Test, so once you learn to spot the patterns in the questions, then you'll be able to select the most efficient way to go about solving the question.

Can you elaborate on this a little?
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by [email protected] » Tue Feb 02, 2016 7:09 pm
Hi prada,

Every prompt that you will face on Test Day is carefully designed - the wording, the numbers, even the wrong answers - are all carefully chosen to make the question fair AND to (often) provide you with more than one approach to get to the correct answer. Since GMAT scores are valid for 5 years, and those scores are comparable over time, just about everything that you'll see when YOU take the GMAT has shown up (in some way, shape or form) on everyone else's GMATs too (the exception is IR, which replaced a second essay prompt back in 2012).

Thus, you really shouldn't think about GMAT questions as 'isolated' prompts - they're based on established rules and patterns. Most Test Takers only focus on the 'knowledge' aspect of their studies though and completely ignore Tactics and the deeper built-in patterns of the Exam. 'Clues' to help you answer the question are often found in the answer choices or in the specific words used in the prompt. For example, in this prompt, the answers are all numbers, written in ascending order. Maybe we can use them 'against' the prompt. Since they're relatively 'spread out', maybe we can use estimation (instead of doing lots of long, drawn out math). With the proper training, you'll learn to spot all of those clues and take advantage of them.

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